PERTEMUAN KE-15
Disusun oleh:
BRILIAN BUDI PRAKOSA, S.T., M.Eng Ir. SOLICHIN, M.T.
Prodi Teknik Sipil FT UNS
Lab. Mekanika Tanah FT UNS, Jl Ir Sutami 36 a Surakarta
GEOLOGI REKAYASA
TKS24082
• Constructive processes (Agradasi) build landforms through tectonic and depositional processes.
– Tectonic processes (ENDOGEN) include movements at plate boundaries, earthquakes, orogeny , deformation, and volcanic activity
– Deposition is the accumulation or accretion of weathered and eroded materials (EKSOGEN)
• Destructive processes (Degradasi) break down landforms through weathering, erosion, and mass wasting (EKSOGEN)
– Weathering is the disintegration of rocks by mechanical, chemical, and biological agents (degradasi).
– Erosion is the removal and transportation of weathered material by water, wind, ice, or gravity (degradasi).
– Mass wasting is the rapid down-slope movement of materials by gravity.
• Other Agents and Processes that Affect Landform Development
– Climate: temperature, precipitation, water cycle, atmospheric conditions – Time: fast and slow rates of change
– People: influences on natural resources and earth surface processes
River System
Boulder Zone
Flood Way Zone
Pastoral Zone
Estuarine Zone
Typical Stream Pattern
Partly fixed Braided Sinuous/
meandering
Distributaries/
often
branched Typical Valley
Section
V shaped vallet
U shaped valley
Erosion Vertical Vertical- Horizontal
Horizontal Horizontal Channel
gradient
5 m/km 1-5 m/km < 1 m/km + 0 m/km
Material Budget
negative Often neutral Usually positive
Positive Predominant
Bed Material
Boulder to cobbles
Gravel to sand
Sand to silt Silt to mud/clay River stadia Young Young-Mature Mature Old –
oxbow lake
Pola Aliran Sungai
wind direction
BACKSLOPE
SLIPFACE
angle of repose
crest
Types of Erosion
The erosion process occurs when water, ice, wind or gravity moves fragments of rock and soil.
The types of erosion are:
Water Erosion
Ice Erosion
Wind Erosion
Mass Movement
Human enhanced erosion
Natural Erosion
Erosion due to Human
Activity
JENIS MATERIAL (SEBELUM GERAKAN) JENIS GERAKAN
TANAH BATUAN TANAH
FALLS (RUNTUHAN) - Rockfall (Runtuhan batuan) - Gerakan sangat cepat (ekstrim
cepat)
Runtuhan bahan rombakan Runtuhan tanah
ROBOHAN Robohan batuan Robohan bahan
rombakan
Robohan tanah Gerakan planar Gerakan rotasi Gerakan planar Gerakan rotasi SLIDES
LONGSORAN
Slump Block glide
Rock slide
Block glide debris
Slump earth flow
MATERIAL LEPAS Fragmen
Batuan
Pasir Lumpur Campuran Tanah Lumpur Pejal non plastis Sangat plastis
Sand run Loessflow Rapid
earth flow
Mudflow FLOWS
(ALIRAN)
K E R I N G
B A S A H
Rock fragment
flow
(Rock fall Avalanche)
Sand/silt flow
Debriss avalache
Debris flow
Slow earth flow
Mud flow
KOMPLEKS Gabungan dari bermacam gerakan tanah biasanya satu macam gerakan tanah lalu diikuti oleh macam gerakan tanah yang lain.